Tumors are commonly thought to result from uncontrolled cell proliferation, i.e. a cell growth which escapes the mechanisms normally regulating it. The cells in a tumor can expand exponentially. Thus, after 20 cell divisions of a single cell, nearly one million cells are formed having a volume of about 1 mm3. After 30 cell divisions, about 1 billion cells are formed having a total volume of 1 cm3. Tumors generally appear to grow spontaneously, anarchically, irregularly and without control by the mechanisms that regulate normal tissue development and morphogenesis. Tumor tissue is thought to be useless tissue that grows at the expense of a healthy organism. Tumor progression often leads to regional and systemic wasting effects.
Although this view stresses some aspects that are typically present in a tumor, it provides little insight into the etiology and pathogenesis of tumors, and provides little understanding of the mechanisms that give rise to the symptoms observed in cancer patients.
What is needed in the art is an understanding of tumor etiology, particularly at the molecular level. The molecular etiology will lead to an understanding of why tumor cell growth appears uncontrolled as well as to an understanding of the mechanisms of activation of the spectrum of phenotypic and pathological molecular mechanisms that are the natural physiological result of the tumor etiology. Only with a true understanding of the etiology of tumor formation at the molecular level can a more comprehensive approach to the detection and treatment of neoplasia can be implemented.